KR20110071087A - A heat exchange unit - Google Patents

Abstract

A mandrel forming spirally wound heat exchange tubes comprises: a roller for forming the tube into a spiral coil; A drive for rotating the roller; A carriage indexing the tube relative to the roller, the roller comprising a plurality of winding beams, the beam to allow for quick setting of the radius of the heat exchange coil formed on the roller. They are arranged to be radially movable by associated powered adjustable supports using coupled power.

Description

Heat exchange unit

The present invention relates to a heat exchange unit and also to a mandrel for producing spirally wound heat exchange tubes. The present application also relates to methods of forming spirally wound heat exchange tubing arrays.

EP1088194, issued to the applicant's predecessor company, is a heat exchange unit intended primarily to recover heat from exhaust gases produced by gas turbines and gas / diesel engines used for offshore platforms and the like. Initiate.

This patent discloses a general layout of a heat exchange unit having an annular heat exchange duct with an array of heat exchange pipes located therein and a bypass duct located concentrically within the heat exchange duct. The cylindrical sleeve valve is located between the two ducts and, as the name implies, duty mode in which gas flows through the heat exchange duct, and bypass mode, the gas flows through the bypass duct, It is movable along its axis to divert the flow of exhaust gas into a bypass mode that does not transfer to the array of heat exchange pipes.

Compared to previous heat exchange units used in these applications, this layout has been found to be small, efficient and safe. In particular, the use of a movable sleeve valve ensures that the flow of exhaust gas is never shut off, which means that there is no danger of back pressure damaging the engine or turbine to which the heat exchange is connected.

Nevertheless, Applicants have recognized that by improving the method of manufacturing a heat exchange unit, the operating efficiency of this type of heat exchange unit can be improved. In addition, improvements can make maintenance of such heat exchange units simple.

The present invention seeks to overcome or at least alleviate the problems of the prior art.

A first aspect of the present invention provides a mandrel for forming spirally wound heat exchange tubes, comprising: a roller for forming the tube into a spiral coil; A drive for rotating the roller; A carriage indexing the tube relative to the roller, the roller comprising a plurality of winding beams, the beam to allow for quick setting of the radius of the heat exchange coil formed on the roller. They provide a mandrel, which is arranged to be movable radially by associated powered adjustable supports using coupled power.

By enabling a powered adjustment to the beams, changeovers are faster than for conventional mandrels that require time-consuming disassembly and reassembly of the mandrels to adjust the radius. ) Can be achieved.

According to a second aspect of the present invention, there is provided a method of forming a heat exchange array using a mandrel according to the preceding paragraph,

a) providing at least one coil support bracket on a winding beam;

b) setting a required radius of the winding beam;

c) maintaining one end of said heat exchange tube on said roller;

d) rotating said roller while supplying said heat exchange tube and indexing said tube along the length of said roller to form a spirally wound tube string;

e) removing the wound string from the roller; And

f) providing a method of forming a heat exchange array comprising repeating steps a) to e) to form additional wound tube strings of different diameters.

A third aspect of the invention is directed to a method of forming a heat exchange array comprising a plurality of spirally wound tube strings using a rotatable mandrel,

a) providing at least one coil support bracket on the roller portion of the mandrel;

b) maintaining one end of a heat exchange tube on said roller;

c) rotating the roller while feeding the heat exchange tube along the length of the roller and indexing the tube to form a first spirally wound tube string;

d) attaching an additional coil support bracket to the coil support bracket of the spirally wound tube string;

e) maintaining one end of a second heat exchange tube in said first spirally wound tube string; And

f) repeating step c) with said second exchange tube.

According to a fourth aspect of the present invention, in a heat exchange unit for hot gas heat recovery,

A duty passage to receive the heat exchange array; A bypass passage disposed concentrically in the tuti passage; And a variable position sleeve valve positioned between the duty passage and the bypass passageway and axially movable to selectively control the flow of gas through the duty passage and the bypass passageway, The plurality of support arms extend at least partially across the duty passage to support a base of the heat exchange array and thereby deliver at least a portion of the weight of the heat exchange array to the body of the unit. To provide heat exchange unit.

Embodiments of the present invention will now be described with reference to the accompanying drawings.

1 is a vertical sectional view through a heat exchange unit according to an embodiment of the present invention in a duty state;
FIG. 2 is a vertical cross sectional view similar to FIG. 1 but in a bypass state;
3 is a side view of a mandrel according to another embodiment of the present invention.
4 is an end view of the mandrel of FIG.
5 is a cross-sectional view along the axis of rotation of the mandrel of FIG. 3 showing the mandrel in two different states.
6 is an isometric cross-sectional view of a support bracket for a heat exchange coil string of the heat exchange unit of FIG. 1 in an unassembled state.
7 shows the bracket of FIG. 6 when assembled with an associated coil string.
8 is an isometric view of blocks of support brackets for holding together a complete array of heat exchange tubing coil strings, with tubing omitted.
FIG. 9 is an isometric view similar to FIG. 8 but showing a larger coil string array. FIG.
10 is an isometric view of blocks of the support brackets of FIG. 8 showing coil strings in situ to form a heat exchange array.
FIG. 11 is a view similar to FIG. 10 but with inlet and outlet manifolds connected to a heat exchange array; FIG.
12 is an isometric vertical cross section through the lower portion of the heat exchange unit of FIG.
13 is an isometric view of the lower portion of FIG. 12.
14 is a plan view of the lower part of FIG. 12;
15 is a vertical section through the lower portion of the unit showing the heat exchange array in situ.
16 is a vertical sectional view through a portion of a heat exchange unit in accordance with another embodiment of the present invention.

The heat exchange unit shown in FIGS. 1 and 2 is an exhaust gas heat recovery unit suitable for use in, for example, offshore oil and gas industries. Such units are generally used in a cylindrical shape and with their long axes oriented vertically. As shown in FIG. 1, such a unit receives hot gas 10 through a gas inlet duct 34 from a gas turbine engine or other type of engine (not shown) and circulates within the heat exchange array 2. It is intended to cool the gas by heat exchange with the fluid, to discharge the cooled gas 18 from the gas outlet duct 7 to the stack, and to send it forward for other use. The heat exchange fluid is sent into and out of the heat exchange array through inlet and outlet manifolds 38 and 39 (see FIG. 11) and can be used as process fluid or to generate steam or the like.

1 and 2 together, the heat exchange unit comprises a generally cylindrical outer casing or sheath comprising an annular heat exchange array 2, an inner sleeve valve 3, and a valve plug 4. shell; 1). The casing 1 and the sleeve valve define a duty passage 22 in which the heat exchange array 2 is located. The sleeve valve 3 is axially slidable in the heat exchange array 2 between two extreme positions.

In FIG. 1, the sleeve valve 3 is shown in its upper extreme position, as a result of which the central passage 19 of the valve sleeve, called the bypass passage, is effectively closed, and generally all exhaust gases are transferred to the heat exchange array 2. Pass). In this position, the gas seal needed to prevent flow through the bypass passage 19 is provided with an upper "knife edge" 14 on the valve plug 4 on the valve plug 4. When contacting a valve seat 13 to be provided.

The valve plug 4 has a downward extension 8 extending axially through a bypass passage 19 concentric with the shell. The extension acts as a flow splitter and has a cylindrical upper portion and a conical end.

In FIG. 2, the sleeve valve 3 is shown in its lower extreme position, with the result that almost all hot gas 10 passes through the bypass passage 19, thus bypassing the heat exchange array 2. . In this position, the lower valve seat 12 on the bottom of the sleeve valve 3 forms a gas seal with a complementary seat 11 attached to the shell 1 under the heat exchange array 2, so that a high temperature Gas 10 passes through bypass passage 19 and exits through valve plug 4 through annular opening 16 between plug 4 and external components.

In operation, the sleeve valve may be located at either of the extreme positions discussed above, or at intermediate positions where some of the flow passes through the duty passage 22 and some passes through the bypass passage 19.

12 and 13, the sleeve valve 3 is attached to the rods 20 at the bottom thereof to move the sleeve valve up and down axially in the heat exchange unit. The rods pass through gas seals (not shown) and are operated by one or more actuation mechanisms 9.

The actuation mechanisms 9 are operated hydraulically, pneumatic, electrically or manually. For example, the rods 20 and therefore the sleeve valve 3 can be raised and lowered by ball screw devices on lead screws driven by electric motors. In addition, there must be at least three rods 20, each rod driven by an actuating mechanism 9, which is equidistantly spaced around the assembly.

The lateral support of the sleeve valve 3 additionally provided by the rods 20 preferably prevents unnecessary vibration of the sleeve valve and can be achieved in a number of different directions. In this embodiment, the downward extension 8 is provided with three guide rails 24 fixed to its outer surface. These guide rails 24 extend in the longitudinal direction of the sleeve and are spaced 120 degrees around it. The sleeve valve 3 is provided with rollers 25 that travel freely along the surface of the rail 24.

In contrast to a heat exchange array of a conventional heat exchange unit, in this embodiment, the array comprises a plurality of spirally wound "strings" of finned heat exchange tubes disposed concentrically in the tuit passage 22. strings) "(30). This device is most clearly seen in FIG. 10 where seven strings 30a to 30g are arranged.

It is preferable to have tubes of equal length for the innermost string 30a in the radial direction with respect to the outermost string 30g so that the fluid in all the strings is heated to the same degree. Thus, the pitch between adjacent windings on the outer string 30g is larger than for the innermost string 30a to account for the larger diameter outermost string 30g.

A mandrel 50 according to an embodiment of the invention for forming such strings 30 is shown in side, end and cross-sectional views in FIGS. 3, 4 and 5, respectively, in a simplified form. As can be seen in FIG. 3, the mandrel is arranged with its axis of rotation A-A being substantially horizontal. A drive arrangement 52 is provided at one end and is arranged to drive the central axle 54 of the main mandrel roller 56. The axles are supported on bearings 58 near their respective ends.

Referring to the end view of FIG. 4, it can be seen that the roller comprises a plurality of beams 60 arranged around its circumference and extending the length of the roller. Although only four beams are shown in FIG. 4, the rollers may have 36 such beams that typically extend parallel to each other at equiangular intervals. In this embodiment, each beam 60 is equipped with three support devices, denoted 62 throughout the specification, which allow the beam to be adjusted radially outward and inward with respect to the axle 54. do. In other embodiments, the number of support devices 62 may vary depending on the desired length of the beam 60.

FIG. 5 shows the extremes of the positions of the beam 60, such a support device comprising pairs of support struts 64 connected about a central pivot point 62 to form a scissor arrangement. It can be seen that it includes. The radially outermost ends of the braces 64 are slidable in axially extending guide slots 68 mounted to the beam 60. The radially innermost ends of the support braces 64 are radially movable of spiders axially moveable under the influence of a hydraulic ram 72 arranged in alignment with the center of rotation of the roller 56. Pivotally connected to the ends of the arms 70 extending in the direction. It will be appreciated that a single hydraulic ram 72 can be connected to all 36 parallel beams arranged by spiders around the circumference of the roller 56 so that each beam 60 can be enlarged and retracted at the same time.

When the rams 72 are fully retracted, the scissor action of the support braces 64 moves the beam 60 connected thereto to their radially outermost position while the hydraulic rams 72 When this is fully magnified, the beams will be in their radially innermost position.

In order to construct a single helical tube string 30, their desired inner radius can be adjusted to provide feedback on the positions of the beam 60 or the adjustable support device 62 via a suitable control system with sensors. Is set first. Therefore, the setting step can be quickly achieved to improve the efficiency of the manufacturing process. Tube support brackets 74 (especially see FIGS. 4, 5, 6) are removably attached to a plurality of beams (typically 6 or 8) and are intended to hold each tube winding in its desired position. do. As can be seen most clearly in FIG. 6, each support bracket 74 has slots 76 formed with 'L' shaped cuts in the flanges and at these cutouts. The tongues thus formed are folded inward to form a channel profile that provides all of the " crenellated " shapes shown in FIG.

It can be seen that the tongues 78 extend across one flange to another to form a box-like structure and can be welded to the opposite flange to reinforce the support bracket 74.

The drive from the drive device 52 is initiated and the finned tube 80 is fed from the indexing carriage 82 to the roller 56. The end of the tube is held in a roller so that the tube is positioned in the slot 76 at the end of one support bracket 74. As the roller 56 rotates, the indexing carriage continues to move along the length of the roller 56 so that the tube 80 is aligned with the appropriate slots on successive support brackets and the correct pitch between adjacent spiral windings is achieved. maintain. The tube 80 can be heated when it is fed to the roller 56 so that a lower bending moment is required to match the shape of the roller.

As can be seen in FIG. 7, once the complete string 30 has been wound over the roller 56, the cover strip 84 is for example by welding to retain the tube 80 in the slots 76. It is attached to each support bracket 74.

Tubes of various lengths may be fed simultaneously toward adjacent slots 76 of the support brackets 74, resulting in a double helical arrangement as shown in FIG. 7. As noted above, the pitch or spacing between adjacent slots 76 can be adjusted to ensure that the length of the tubing of each string in the heat exchange array is made approximately the same. Once the string is complete, it can be removed from the mandrel roller 56 and the beam radius is readjusted to advance to the next string of the heat exchange array.

If all strings 30 are manufactured using the method described above and any subsequent heat treatment to remove residual stresses is performed, the strings are placed in a concentric " Russian Doll " array 2 shown in FIG. Can be assembled together. This can be done in situ on the heat exchange unit or away from it.

In either case, the tops of the strings 30 have bolts extending through holes in the tie-bars and corresponding bores 88 at the ends of each support bracket 74. By means of connection with the tie-bars 86. In one embodiment, similar bottom tie bars 87 may connect the bottoms of the strings but they have an additional channel 89 extending downwards to connect to the supports in the heat exchange unit. Alternatively, the bottoms of the support brackets can connect directly to the supports.

The adjustable mandrel 50 is used to individually form single strings 30 of coiled tubing, as well as multiple strings undergoing a "coil-on-coil" process. Can be stacked on the mandrel. In this process, the inner radius of the heat exchange array 2 is set by the beam 60, but once the innermost string is completed, the support brackets for the next string are supported brackets 74 (eg, for the first string). By means of welding) and the finned tube 80 is wound on these brackets. The process is repeated until all the strings making up the heat exchange array 2 are completed. The entire heat exchange array 2 is then removed from the mandrel roller 56 all at once.

In other embodiments, a standard mandrel may be used for the coil-on-coil method but the inner diameter may be fixed.

12 to 15, the support device for the heat exchange array 2 can be seen more clearly. In these figures, six heat exchange array support arms 90 are mounted to the outer casing 1 and extend radially inward in a cantilevered manner. These figures show the lower tie-bars 87 for the support brackets 74 attached to the arms 90. Therefore, as shown in FIG. 15, if the heat exchange array 2 is placed on top of the support brackets 90 during assembly, the tie-bars 87 can be secured to the support brackets 74 in place and The array 2 is supported by the arms 90.

As a result of this arrangement, if the tube strings 30 are only supported by the arms 90 and are not connected to their adjacent strings, the tie bars 86 are removed from the top of the strings and the bottom tie-bars 87 It is possible to retighten the bolts connecting the special strings and to remove the strings 30 separately from the heat exchange unit 2, while the rest are still in place. If a failure occurs in the individual coil strings 30, this can significantly ease maintenance of the unit. It is also possible to lift the individual strings 30 one by one into the place above the heat exchange unit, which means that a low capacity crane or hoist can be used during assembly.

Also shown in FIGS. 12-15 are three substantially cylindrical cooling tubes 42. These tubes 43 are located in the space below the heat exchange array 2 and extend upwards from the casing 1, where the casings taper inwardly to meet the inlet duct 34. Each tube 42 is provided with a feed of ambient temperature air from a fan (not shown) through a manifold (not shown). Each of the tubes 42 is formed with a number of vent holes to allow air to escape.

When the heat exchange unit is in the bypass state, air is sent through the cooling tubes 42 and this provides two functions. First, it helps to equalize the pressure between the bypass passage 19 and the duty passage 22 as the exhaust gas passes through the bypass passage. This helps to minimize the exhaust gases that may pass through the bottom valve seat 12 and to continue heating to some extent with the fluid in the tubes of the heat exchange array 2.

In addition, when in the bypass mode, heat from the exhaust gas inevitably continues to radiate to some extent into the heat exchange array 2. The flow of cooling air from the cooling tubes 42 over the heat exchange array 2 helps to eliminate or at least minimize this heating effect. In a conventional heat exchange unit, it was necessary to install a dump cooler to cool the fluid separately if the fluid resided in the heat exchange array 2 for a considerable period of time. The cooling tubes 42 eliminate the need for a dump cooler in this embodiment.

FIG. 16 shows a particularly preferred arrangement of the control rods 20 and the cooling tubes 42 ′ for the sleeve valve 3. In this embodiment of the present invention, the cooling tubes 42 'and cylindrical housing 44 for the rods serve as supports for the heat exchange array support arms 90'. As a result, the connection strength of the support arms 90 'to the casing can be reduced compared to the cantilevered arms of the embodiment of FIGS. 12-15, or no connection to the casing 1 can be provided.

The various features of the invention outlined above provide a heat exchange unit that is more efficient in operation and easier to manufacture, assemble and maintain.

It will be understood that various modifications may be made within the scope of the present invention. The heat exchange unit may be adapted to work with its long axis arranged substantially in the horizontal direction. The gas can be sent to flow downwards rather than upwards with minor changes to the unit. The rack extends radially outward to move the beam directly, or to adjust the diameter of the electric motor and the mandrel, such as the rack and pinion gear arrangement, replacing the hydraulic rams in the assembly of FIG. Various variations on the scissor and hydraulic ram arrangements can be provided.

2: heat exchange array 3: sleeve valve
4, 44: valve plug 7: gas outlet duct
8: downward extension 9: bypass passage
10 hot gas 11 outer casing
12: lower valve seat 13: valve seat
14: knife edge 16: annular opening
18: cooled gas 19: bypass passage
20: load 22: duty passage
24: guide rail 25: roller
30, 30a to 30g: string 34: gas inlet duct
38, 39: inlet and outlet manifold 50: mandrel
52 drive device 54 center axle
58: bearing 60: beam
64: brace 68: guide slot

Claims (20)

In a mandrel forming spirally wound heat exchange tubes,
A roller for forming the tube into a spiral coil;
A drive for rotating the roller;
A carriage indexing the tube relative to the roller, the roller comprising a plurality of winding beams, the beam to allow for quick setting of the radius of the heat exchange coil formed on the roller. The mandrel is arranged to be movable radially by associated powered adjustable supports using coupled power. The method of claim 1,
And the supports comprise a hydraulic ram for carrying out the adjustment. The method of claim 1,
The support includes a motor and a gear device. The method of claim 3, wherein
The gear device has a rack and a pinion gear. The method according to any one of claims 2 to 4,
The adjustment is performed by a scissor arrangement of support struts. 6. The method according to any one of claims 1 to 5,
At least one winding beam includes a slotted coil support bracket for maintaining a pitch between adjacent sections of the helix. A method of forming a heat exchange array using a mandrel according to any one of claims 1 to 6, wherein
a) providing at least one coil support bracket on a winding beam;
b) setting a required radius of the winding beam;
c) maintaining one end of said heat exchange tube on said roller;
d) rotating said roller while supplying said heat exchange tube and indexing said tube along the length of said roller to form a spirally wound tube string;
e) removing the wound string from the roller; And
f) repeating steps a) to e) to form additional wound tube strings of different diameters. The method of claim 7, wherein
And g) attaching together the two wound tube strings. The method of claim 8,
In step g) at least two wound tube strings are attached together through the coil support brackets. The method according to any one of claims 7 to 9,
In step c), said tube is held in said coil support bracket. The method according to any one of claims 7 to 10,
After step d), further comprising h) securing a cover over the wound tube string on the coil support bracket to hold the wound tube string tube in position on the bracket. A method of forming a heat exchange array comprising a plurality of spirally wound tube strings using a rotatable mandrel, the method comprising:
a) providing at least one coil support bracket on the roller portion of the mandrel;
b) maintaining one end of a heat exchange tube on said roller;
c) rotating the roller while feeding the heat exchange tube along the length of the roller and indexing the tube to form a first spirally wound tube string;
d) attaching an additional coil support bracket to the coil support bracket of the spirally wound tube string;
e) maintaining one end of a second heat exchange tube in said first spirally wound tube string; And
f) repeating step c) with said second exchange tube to form a second spirally wound tube string. The method of claim 12,
Prior to step a), further comprising the step g) of setting the required radius of the roller portion. The method according to claim 12 or 13,
And in step b) said tube is held in said coil support bracket. The method according to any one of claims 12 to 14,
Between step c) and step d), further comprising g) securing a cover over the wound tube string on the coil support bracket to hold the wound tube string in position on the bracket. Way. A heat exchange unit for hot gas heat recovery,
A duty passage to receive the heat exchange array;
A bypass passage disposed concentrically in the tuti passage; And
A variable position sleeve valve positioned between the duty passage and the bypass passage and axially movable to selectively control the flow of gas through the duty passage and the bypass passage; Supporting arms extend at least partially across the duty passage to support a base of the heat exchange array and thereby deliver at least a portion of the weight of the heat exchange array to the body of the unit. unit. 17. The method of claim 16,
And the support arm cantilevered from an outer wall of the duty passage. 17. The method of claim 16,
A support brace extends from the base of the duty passage to support the support beam. The method of claim 18,
The support brace is provided with at least one vent so that cooling air can be introduced into the heat exchange duct when the sleeve is in the bypass position to prevent unwanted heating of the fluid in the heat exchange array. A heat exchange unit further comprising a supply tube. The method of claim 18,
The support brace further comprises a portion of the means for adjusting the position of the sleeve valve device.

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